From mboxrd@z Thu Jan 1 00:00:00 1970 From: "Michael S. Tsirkin" Subject: Re: [PATCH 1/6] virtio_balloon: transitional interface Date: Mon, 30 Mar 2015 19:55:53 +0200 Message-ID: <20150330195508-mutt-send-email-mst@redhat.com> References: <1427737006-23191-1-git-send-email-mst@redhat.com> <1427737006-23191-2-git-send-email-mst@redhat.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Content-Disposition: inline In-Reply-To: <1427737006-23191-2-git-send-email-mst-H+wXaHxf7aLQT0dZR+AlfA@public.gmane.org> Sender: linux-api-owner-u79uwXL29TY76Z2rM5mHXA@public.gmane.org To: linux-kernel-u79uwXL29TY76Z2rM5mHXA@public.gmane.org Cc: virtio-dev-sDuHXQ4OtrM4h7I2RyI4rWD2FQJk+8+b@public.gmane.org, virtualization-cunTk1MwBs9QetFLy7KEm3xJsTq8ys+cHZ5vskTnxNA@public.gmane.org, Rusty Russell , linux-api-u79uwXL29TY76Z2rM5mHXA@public.gmane.org List-Id: linux-api@vger.kernel.org On Mon, Mar 30, 2015 at 07:37:12PM +0200, Michael S. Tsirkin wrote: > Virtio 1.0 doesn't include a modern balloon device. > But it's not a big change to support a transitional > balloon device: this has the advantage of supporting > existing drivers, transparently. > > Signed-off-by: Michael S. Tsirkin > --- Hmm, re-reading the code, this won't be enough for BE guests. We are doing one extra byteswap there. I'll fix up and repost. > include/uapi/linux/virtio_balloon.h | 6 ++++++ > drivers/virtio/virtio_balloon.c | 8 ++++++-- > 2 files changed, 12 insertions(+), 2 deletions(-) > > diff --git a/include/uapi/linux/virtio_balloon.h b/include/uapi/linux/virtio_balloon.h > index 4b0488f..5d83902 100644 > --- a/include/uapi/linux/virtio_balloon.h > +++ b/include/uapi/linux/virtio_balloon.h > @@ -56,4 +56,10 @@ struct virtio_balloon_stat { > __u64 val; > } __attribute__((packed)); > > +struct virtio_balloon_stat_modern { > + __u8 reserved[6]; > + __u16 tag; > + __u64 val; > +}; > + > #endif /* _LINUX_VIRTIO_BALLOON_H */ > diff --git a/drivers/virtio/virtio_balloon.c b/drivers/virtio/virtio_balloon.c > index 6a356e3..68e937f 100644 > --- a/drivers/virtio/virtio_balloon.c > +++ b/drivers/virtio/virtio_balloon.c > @@ -77,7 +77,7 @@ struct virtio_balloon { > > /* Memory statistics */ > int need_stats_update; > - struct virtio_balloon_stat stats[VIRTIO_BALLOON_S_NR]; > + struct virtio_balloon_stat_modern stats[VIRTIO_BALLOON_S_NR]; > > /* To register callback in oom notifier call chain */ > struct notifier_block nb; > @@ -269,7 +269,11 @@ static void stats_handle_request(struct virtio_balloon *vb) > vq = vb->stats_vq; > if (!virtqueue_get_buf(vq, &len)) > return; > - sg_init_one(&sg, vb->stats, sizeof(vb->stats)); > + if (virtio_has_feature(vdev, VIRTIO_F_VERSION_1)) > + sg_init_one(&sg, vb->stats, sizeof(vb->stats)); > + else > + sg_init_one(&sg, &vb->stats->tag, sizeof(vb->stats) - > + offsetof(typeof(*vb->stats, tag); > virtqueue_add_outbuf(vq, &sg, 1, vb, GFP_KERNEL); > virtqueue_kick(vq); > } > -- > MST >